Protein Kinase C Enhances Exocytosis from Chromaffin Cells by Increasing the Size of the Readily Releasable Pool of Secretory Granules

• DOI: 10.1016/s0896-6273(00)80147-6
• Publication Date: 2004-04-13T09:31:41Z
• Authors: Kevin D. Gillis; Rotraut Mößner; Erwin Neher
• Keywords: Kinetics; 0303 health sciences; 03 medical and health sciences; Dose-Response Relationship, Drug; Neuroscience(all); Chromaffin System; Animals; Calcium; Cattle; Exocytosis; Protein Kinase C; Membrane Potentials

We have used membrane capacitance measurements to assay Ca2+-triggered exocytosis in single bovine adrenal chromatin cells. Brief application of phorbol ester (PMA) enhances depolarization-evoked exocytosis severalfold while actually decreasing the Ca2+ current. Ca2+ metabolism is unchanged. Three different protocols were used to show that PMA increases the size of the readily releasable pool of secretory granules. PMA treatment leads to a large increase in amplitude, but little change in the time course of the exocytic burst that results from rapid elevation of [Ca2+]i upon photolysis of DMI-Nitrophen. Thus, PKC appears to affect a late step in secretion but not the Ca2+ sensitivity of the final step.